/*
* 剑指 Offer II 097. 子序列的数目
* */
public class jianzhi97 {

    public int numDistinct(String s, String t) {
        int m = s.length(), n = t.length();
        int dp[][] = new int[m + 1][n + 1];
        dp[0][0] = 1;
        for (int i = 1; i <= m; i++){
            dp[i][0] = 1;
            for (int j = 1; j <= n; j++){
                if(s.charAt(i - 1) == t.charAt(j - 1)){
                    dp[i][j] = dp[i - 1][j - 1] + dp[i - 1][j];
                }else{
                    dp[i][j] = dp[i - 1][j];
                }
            }
        }
        return dp[m][n];
    }
}
